Does the Legally Binding Character of the Paris Climate Change Agreement Matter and, If So, Why?

December 4, 2015

François Hollande addressing world leaders at COP21. CREDIT:COP 21 (CC)

Will the Paris climate change agreement be more effective if it is a legal rather than a political instrument, and if parties' nationally determined contributions to reduce emissions (NDCs) are legally binding obligations rather than non-binding aims? How much does the legal form of the Paris outcome matter? Opinions on these questions differ widely.1

The effectiveness of an international regime is a function of three factors: (1) the ambition of its provisions; (2) the level of participation by states; and (3) the degree to which states comply (Barrett 2003). Those who argue for the importance of a legally binding outcome in Paris focus primarily on compliance. But the legally binding character of the Paris agreement or its constituent elements could also affect ambition and participation, potentially in negative ways. So even if legal bindingness promotes compliance, as proponents argue, it may not increase effectiveness if its positive effects on compliance are outweighed by negative effects on participation and/or ambition.

In theory, the legal character of the Paris agreement might promote compliance in a number of ways, even in the absence of judicial application or enforcement (Abbott and Snidal 2002). First, treaties must be formally ratified by states, usually with the approval of the legislature. So acceptance of a treaty generally signals greater domestic buy-in and commitment than acceptance of a political agreement, which typically can be done by the executive acting alone.

Second, the internal sense of legal obligation, if sincerely felt, means that legal commitments exert a greater 'compliance pull' than political commitments, independent of any enforcement.

Third, to the extent that states take legal commitments more seriously than political commitments, this not only makes them more likely to self-comply; it causes them to judge non-compliance by other states more harshly. As a result, states risk greater costs to their reputation and to their relations with other states if they violate a treaty commitment than a political commitment, making non-compliance less attractive.

Fourth, legally binding agreements tend to have greater effects on domestic politics than political agreements, through their influence on bureaucratic routines and by helping to mobilize and empower domestic advocates.

Finally, legal obligations are at least capable of being applied by courts. So if legalized dispute settlement is available, either in an international tribunal or a state's domestic courts, then the legal character of the Paris agreement would be a necessary condition of using these procedures.

Perhaps the best evidence that states take legal commitments more seriously than political commitments is that they are more careful in negotiating and accepting them—and, in many states, acceptance of treaties requires special procedures, such as legislative approval. This caution would be irrational if legal bindingness didn't matter. The fact that treaties are more difficult to negotiate and to approve than non-legal instruments suggests that states view them as imposing a greater constraint on their behavior.

But while there are good reasons to believe that legal form enhances compliance, other factors are also important. In particular, transparency and accountability mechanisms make it more likely that poor performance will be detected and criticized, thereby raising the reputational costs for the state concerned, regardless of whether a norm is legally binding. Like legal commitment, transparency and accountability mechanisms can also help mobilize and empower domestic supporters of an agreement. In addition, the precision of an instrument can enhance effectiveness, both because precise norms exert greater normative guidance and because violations are more apparent.

As a result of these factors, non-legal instruments can significantly affect behavior (Victor et al. 1998, Shelton 2000). Indeed, the 1975 Helsinki Declaration2 has been one of the most successful human rights instruments, despite its explicitly non-legal nature, because of its regular review conferences, which provided domestic advocates with a basis for mobilization and which focused international scrutiny on the Soviet bloc's human rights performance.

Similarly, with respect to ambition, the legal character of an agreement can cut both ways. On the one hand, it may make states willing to assume more ambitious commitments, by giving them greater confidence that their actions will be reciprocated by others. On the other hand, it may also have a negative effect on ambition, if states are more concerned about locking themselves into potentially costly commitments than about non-compliance by other states.

Finally, since states are cautious about entering into legal agreements (or have special requirements for ratification that raise additional hurdles), making an instrument legally binding may reduce participation. The United States declined to participate in the Kyoto Protocol, in part, because of the legally binding nature of Kyoto's emission targets and the impossibility of getting Senate consent to ratification. Similarly, far fewer countries, arguably, would have participated in the Copenhagen Accord, by putting forward emissions pledges, if the Accord had been a legally binding instrument that made countries' pledges legally binding.

How do these countervailing factors play out? Thus far, it has been next to impossible to answer this question empirically. To do so, one would need to hold all other factors constant, and vary only the legal form of an agreement. Despite significant efforts over the last two decades to determine the significance of legal bindingness internationally, we still do not have any definitive answers (Stavins et al. 2014).

One thus cannot definitively say how much the legally binding character of the Paris agreement matters. Making the agreement legally binding may provide a greater signal of commitment and greater assurance of compliance. But transparency, accountability, and precision can also make a significant difference, and legal bindingness can be a double-edged sword if it leads states not to participate or to make less ambitious commitments. Thus, the issue of legal form, though important, should not be fetishized as a measure of the Paris conference's success.

This excerpt has been reprinted with kind permission. Source:

"Legally Binding Versus Non-legally Binding Instruments" by D. Bodansky. Reprinted from Towards a Workable and Effective Climate Regime edited by Scott Barrett, Carlo Carraro, and Jaime de Melo.

D. Bodansky "Avantages et Inconvénients d'instruments juridiques contraignants" in Scott Barrett, Carlo Carraro and Jaime de Melo eds. Vers une Politique du climat réaliste et efficace, ECONOMICA, Paris.


Abbott, K. and D. Snidal (2000), "Hard and Soft Law in International Governance," International Organization 54(3): 421-456.

Barrett, S. (2003), Environment and Statecraft: The Strategy of Environmental Treaty-Making, Oxford: Oxford University Press.

Downs, G., D. Rocke and P. Barsoom (1996), "Is the Good News about Compliance Good News about Cooperation?," International Organization 50(3): 379-406.

Shelton, D. (ed.) (2000), Commitment and Compliance; The Role of Non-Binding Norms in International Law, Oxford: Oxford University Press.

Simmons, B. (2009), Mobilizing for Human Rights: International Law in Domestic Politics, New York: Cambridge University Press.

Stavins, R., J. Zou et al. (2014), International Cooperation: Agreements and Instruments, in Climate Change 2014: Mitigation of Climate Change, Cambridge, UK: Cambridge University Press.

Victor, D., K. Raustiala and E. Skolnikoff (eds) (1998), The Implementation and Effectiveness of International Environmental Law, Cambridge, MA: MIT Press.


1 On the effectiveness of international law, compare Downs et al. (1996) with Simmons (2009).

2 Conference on Security and Cooperation in Europe, Final Act (1 August 1975), Article 10 in International Legal Materials 14: 1292.